Cardiac ablation catheters and method

ABSTRACT

A catheter uses a steerable outer catheter with an inner catheter rotatable and extendable with respect to the outer catheter. The outer catheter may be positioned within a patient&#39;s heart and a portion of the outer catheter may provide movement like that of a windshield wiper by manipulation of a spring. By combining the windshield wiper type movement with the extension and rotation of the inner catheter relative to the outer catheter, a large area within a patient&#39;s heart may be readily mapped for conduction tissue and be subjected to laser ablation if appropriate. Various configurations provide flexibility in relatively positioning of windows used to apply laser energy and ring electrodes used to sense conduction tissue.

This is a divisional of application Ser. No. 08/123,207 filed Sep. 20,1993 now U.S. Pat. No. 5,464,404.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus and method for treating cardiacor similar conditions in a patient. More specifically, this inventionrelates to mapping of, and application of laser energy, to the tissuesof a patient.

The use of laser beams for treatment of medical conditions has been wellknown. Various devices have also been developed for application of laserenergy to tissue inside of a patient.

In order to provide laser energy to tissue within a patient for suchpurposes as ablation of plaque from the walls of a blood vessel, atechnique is required which can accurately apply the laser energy to thetissue. Various problems have been encountered in application of laserenergy to tissues of a patient. For example, the laser passing through aglass window may cause the build up of burnt tissue or burnt blood cellsat and around the point at which the laser exits the glass window. Thisblack, carbonized material would in turn absorb the laser energy beforeit could strike the tissue and would at least partially block the laserenergy from striking the tissues of the patient. This may damage thelaser catheter device itself.

George S. Abela and Stephan E. Friedl, both among the inventors of thepresent application, obtained U.S. Pat. No. 5,061,265 on Oct. 29, 1991,entitled "LASER TREATMENT APPARATUS AND METHOD", hereby incorporated byreference. That patent discloses a dual hood arrangement whereby laserenergy passes out through an inner hood having a window of transparentmaterial and passes through an opening of an outer hood. By supplyingpressurized flushing solution to within the outer hood, the flushingsolution maintains the inner hood relatively clear of burned materialsand flows out the same opening as the laser energy.

Among other prior patents, U.S. Pat. No. 4,860,743, issued Aug. 29, 1989to George S. Abela and U.S. Pat. No. 5,041,109, issued Aug. 20, 1991 toGeorge S. Abela, both disclose various laser catheters for treatment ofcardiac conditions. Those patents, both of which are hereby incorporatedby reference, disclose the use of electrode rings on the catheters fordetection of conduction tissue. Such rings are also discussed in theAbela et al '265 patent mentioned above. The electrode rings allow oneto locate tissue which is to be treated.

Although the above and various other designs of catheters have beenquite useful, they have often been subject to one or more of severallimitations or disadvantages. For example, positioning of the catheterswithin the patient has often been difficult and/or very time-consuming.The problem of positioning of the catheter for proper application of thelaser energy is evident in treatment of arrhythmia conditions. Use ofelectrodes for mapping the conduction tissues of the heart has oftenbeen less efficient than desirable. The prior arrangements have oftenbeen less than satisfactory for AV (atrial-ventricular) nodal ablation.Generally, the fixed relationship between the laser beam and theelectrodes has reduced flexibility in treating various conditions.

Among other problems with catheters in which flushing solution is used,body fluids may undesirably enter into the catheter through the portfrom which flushing solution is supplied during any halt in the supplyof the flushing solution. That is, if one wishes to halt the supply offlushing solution temporarily, blood or other bodily fluids may enterinto the port and the associated passage or channel used to supply theflushing solution.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providenew and improved catheter designs and an associated method.

A more specific object of the present invention is to provide a catheterdesign which has a great deal of flexibility and adaptability inpositioning.

A further object of the present invention is to provide a catheterallowing for variations in the relationship between the window used tosupply laser energy and other parts of the catheter.

A further object of the present invention is to provide for thestabilization of the position of a large part of the catheter, whileallowing variations in positioning of a window used to supply laserenergy.

Yet another object of the present invention is to provide variousdifferent relationships between a window and electrodes used to senseconduction tissue.

A still further object of the present invention is to provide atechnique for minimizing the ability of bodily fluids to enter into thecatheter.

Yet another object of the present invention is to provide a steeringdevice for a catheter.

The above and other objects of the present invention which will be morereadily understood when the following detailed description is consideredin conjunction with the accompanying drawings are realized by anapparatus for patient treatment having an outer catheter with a proximalend and a distal end having at least a first passage extendinglengthwise therein. (As used herein, "patient treatment" shall includediagnosis of patient conditions as well as application of techniques toimprove patient conditions.) An inner catheter is disposed at leastpartly in the first passage and has a proximal end and a distal end. Theinner catheter has a side wall, a window in the side wall, and anoptical fiber having a tip. The window is positioned such that light maypass between the tip and a light communicating part of the window. (Asused herein, a "window" shall include both an opening through whichlight may pass as well as a light passage with material which istransparent to light.) The inner catheter has an extending portionextendable out the distal end of the outer catheter by a variableamount. Lengthwise offset first and second electrodes are used. Thefirst electrode is mounted on an external surface of the side wall andthe second electrode is mounted either on the external surface of theside wall or an external surfaces of the outer catheter.

The first and second electrodes are operable for detecting the presenceof conductive cardiac tissue. A steering means is used for steering theouter catheter. The inner catheter is rotatable relative to the outercatheter.

In one embodiment, the second electrode is on the external surface ofthe side wall and a third electrode is disposed on the external surfaceof the outer catheter.

In another embodiment, the second electrode is on an external surface ofthe outer catheter such that extension of the inner catheter relative tothe outer catheter varies the distance between the first and secondelectrodes.

The first and second electrodes have contact surfaces which are limitedto an angular range excluding at least a back part of the side wallradially opposite the window. The first and second electrodes arerespectively first and second rings and a back part of each ring iscovered by insulating material in a specific arrangement.

One embodiment uses a third electrode with the second and thirdelectrodes both mounted on the external surface of the side wall fordetecting the presence of conductive cardiac tissue. That embodiment maymore specifically include a fourth electrode also mounted on theexternal surface of the side wall for detecting the presence ofconductive cardiac tissue.

In one aspect of the present invention, the window is lengthwise outsidea zone including the first and second electrodes and a spacetherebetween.

In one embodiment or aspect of the present invention, the firstelectrode may have a contact surface which completely surrounds thewindow.

In another embodiment or aspect of the present invention, the window mayhave at least a first valve member for selectively opening and closingthe window.

One embodiment of the present invention may use a second window in theside wall which is lengthwise offset from the previously mentioned orfirst window. The optical fiber is movable between a position in whichlight passes between the tip and the first window and a position inwhich light passes between the tip and, the second window.

The optical fiber is operable to carry laser energy to cardiac tissuesof a patient. The window is more specifically an opening for passage oflight and flushing solution.

The steering means in one embodiment is disposed within a second passagein the outer catheter.

In another embodiment, the steering means includes a coil spring mountedto the distal end of the outer catheter, two control lines attached tothe coil, and a control means for bending the coil spring bymanipulating the control lines.

The present invention may also be described as an apparatus for patienttreatment including:

an outer catheter having a proximal end and a distal end having at leasta first passage extending lengthwise therein;

an inner catheter movably disposed at least partly in the first passageand having a proximal end and a distal end, the inner catheter having aside wall, a first window in the side wall, and an optical fiber havinga tip, the first window positioned such that light may pass between thetip and a light communicating part of the first window, the innercatheter having an extending portion extendable out the distal end ofthe outer catheter;

lengthwise offset first and second electrodes, the first electrodemounted on an external surface of the side wall and the second electrodemounted on a surface selected from the group consisting of: the externalsurface of the side wall and an external surface of the outer catheter,the first and second electrodes operable for detecting the presence ofconductive cardiac tissue; and

a steering means for steering the outer catheter; and

wherein the steering means includes a coil spring mounted near thedistal end of the outer catheter, two control lines attached to thecoil, and a control means for bending the coil spring by manipulatingthe control lines.

The present invention may alternately be described as an apparatus forpatient treatment including:

an outer catheter having a proximal end and a distal end having at leasta first passage extending lengthwise therein; an inner catheter disposedat least partly in the first passage and having a proximal end and adistal end, the inner catheter having a side wall, a first window in theside wall, and an optical fiber having a tip, the first windowpositioned such that light may pass between the tip and a lightcommunicating part of the first window, the inner catheter having anextending portion extendable out the distal end of the outer catheter;

lengthwise offset first and second electrodes, the first electrodemounted on an external surface of the side wall and the second electrodemounted on a surface selected from the group consisting of: the externalsurface of the side wall and an external surface of the outer catheter,the first and second electrodes operable for detecting the presence ofconductive cardiac tissue; and

a steering means for steering the outer catheter; and

wherein the inner catheter is rotatable relative to the outer catheter.

The present invention may alternately be described as an apparatus forpatient treatment including:

a housing with a side wall;

a first window in the side wall;

an optical fiber having a tip, the first window positioned such thatlight may pass between the tip and a light communicating part of thefirst window; and

lengthwise offset first and second electrodes mounted to the side walland operable for detecting the presence of conductive cardiac tissue;and

wherein the side wall includes first and second portions on which thefirst and second windows are respectively disposed, and the firstportion is movable relative to the second portion to vary the distancebetween the first and second electrodes.

The present invention may alternately be described as an apparatus forpatient treatment including:

a housing with a side wall;

a first window in the side wall;

an optical fiber having a tip, the first window positioned such thatlight may pass between the tip and a light communicating part of thefirst window; and

lengthwise offset first and second electrodes mounted to the side walland operable for detecting the presence of conductive cardiac tissue;and

wherein the first and second electrodes have contact surfaces which arelimited to an angular range excluding at least a back part of the sidewall radially opposite the first window.

The present invention may alternately be described as a method ofpatient treatment with the steps of:

inserting an apparatus at least partly in a patient, the apparatushaving:

an outer catheter having a proximal end and a distal end having at leasta first passage extending lengthwise therein;

an inner catheter disposed at least partly in the first passage andhaving a proximal end and a distal end, the inner catheter having a sidewall, a first window in the side wall, and an optical fiber having atip, the first window positioned such that light may pass between thetip and a light communicating part of the first window, the innercatheter having an extending portion extendable out the distal end ofthe outer catheter by a variable amount;

lengthwise offset first and second electrodes, the first electrodemounted on an external surface of the side wall and the second electrodemounted on a surface selected from the group consisting of: the externalsurface of the side wall and an external surface of the outer catheter,the first and second electrodes operable for detecting the presence ofconductive cardiac tissue; and

a steering means for steering the outer catheter;

using the steering means to position the distal end of the outercatheter at a desired location within the patient;

extending the extending portion of the inner catheter, while an anchorpoint on the outer catheter remains stationary; and

using the steering means to pivot the distal end of the inner catheterrelative to the anchor point.

The present invention may alternately be described as a method ofpatient treatment with the steps of:

inserting a catheter at least partly within a patient, the catheterhaving:

a housing with a side wall;

a first window in the side wall;

an optical fiber having a tip, the first window positioned such thatlight may pass between the tip and a light communicating part of thefirst window;

lengthwise offset first and second electrodes mounted to the side walland operable for detecting the presence of conductive cardiac tissue;and

a steering means for steering the catheter including a spring means forbending the catheter;

using the steering means to position a distal end of the catheter at adesired location within a patient's heart such that the spring means isbent so as to push a distal portion of the catheter against a wall ofthe patient's heart and thus maintain the first and second electrodes incontact with the wall of the patient's heart, even during all parts ofthe heart beat.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will be morereadily understood when the following detailed description is consideredin conjunction with the accompanying drawings wherein like charactersrepresent like parts throughout the several views and in which:

FIG. 1 shows a simplified perspective view of a first embodiment of thepresent invention with a block diagram of a laser;

FIG. 2 shows a cross section view taken along lines 2--2 of FIG. 1;

FIG. 3 shows a cross section view with parts broken away of an outercatheter;

FIG. 4 shows a perspective view of a controller and associatedcomponents used with the present invention;

FIGS. 5A, 5B, and 5C are simplified operational diagrams illustratingthe relationship between a control knob and the distal end of thecatheter when the control knob is in three different positions;

FIG. 6 shows a simplified longitudinal cross section of a patient'sheart with the catheter system of the, present invention in place;

FIG. 7 shows a simplified cross section taken along lines 7--7 of FIG.6;

FIG. 8 shows a second embodiment inner catheter according to the presentinvention;

FIG. 9 shows a third embodiment inner catheter according to the presentinvention;

FIG. 10 shows a fourth embodiment inner catheter according to thepresent invention;

FIG. 11 shows a fifth embodiment inner catheter according to the presentinvention;

FIG. 12 shows a sixth embodiment inner catheter according to the presentinvention;

FIG. 13 shows a seven embodiment inner catheter;

FIG. 14 shows an eighth embodiment inner catheter according to thepresent invention;

FIG. 15 is a side view of the inner catheter of FIG. 14;

FIG. 16 is a cross-section of a patient's heart with a ninth catheterdesign; and

FIGS. 17A, 17B, and 17C are simplified operational diagrams illustratingthe relationship between a control knob and the distal end of thecatheter when the control knob is in three different positions for thecatheter of FIG. 16.

DETAILED DESCRIPTION

With reference now to FIG. 1, a catheter system or catheter 10 accordingto the present invention will be described. The catheter 10 includes anouter or introducer catheter 12 and an inner catheter 14. The innercatheter 14 is preferably a dual hood laser catheter built in the mannerdiscussed and shown in the incorporated by reference Abela et al '265patent with possible modifications as hereafter discussed. Among otherdifferences, the optional tube and guide wire of the incorporated byreference patent would usually not be used in the design of innercatheter 14 since positioning of the inner catheter 14 will beaccomplished by positioning of the outer catheter 12 in the mannerdiscussed in more detail below.

The inner catheter 14 has a window 16 through which laser energy 16L maybe applied to tissues, such as cardiac tissues, of a patient (tissuesand patient not shown). More specifically, the first window 16 would bean opening through which the laser energy 16L passes and through which aflushing solution 16F is sprayed. The flushing solution 16F will havebeen injected into a proximal end 14P of the inner catheter 14 bysupplying the flushing solution to input port 18P of a relativelystandard Y connector 18. First and second ring electrodes 20F and 20Sare disposed on the external surface of the cylindrical side wall 14C ofinner catheter 14. The ring electrodes 20F and 20S are used for sensingcardiac conduction tissue in a manner described in more detail in thethree incorporated by reference patents.

Although the inner catheter 14 may be constructed substantiallyidentically to the catheter designs disclosed in the incorporated byreference Abela et al '265 patent, the inner catheter 14 of the presentinvention would generally have only a single or first window 16 forapplying the laser energy 16L. The window 16 would be an opening in the1 wall 14C. An optical fiber 22 carries laser energy from laser 24 intothe proximal end 14P of inner catheter 14, the optical fiber 22 having atip located adjacent to the window 16 such that laser energy supplied bylaser 24 is carried out the window opening 16 as energy 16L. Althoughnot shown, a rotational coupling unit could be used to allow fiber 22 torotate relative to laser 24 while maintaining a beam from the laser inalignment with the entry end of the optical fiber. As shown, the distalend 14D of inner catheter 14 may include a first portion 14F having thesame cylindrical configuration and diameter throughout the innercatheter 14 from ring electrode 20F to the entry location of opticalfiber 22 illustrated schematically. Optionally, the inner catheter 14may include a second section 14S, which is cylindrical and has a largerdiameter than section 14F. The second section 14S may have the sameouter diameter as the outer diameter of outer cathode 12. The secondsection 14S could be a separate piece of catheter side wall materialadhered or otherwise fixed to portion 14F or, alternately, the same sidewall tube making up portion 14F may simply have an enlarged outerdiameter for the section 14S. The materials used for sections 14S and14F, and also used more generally for inner catheter 14 and outercatheter 12, may be any of various catheter materials described in theincorporated by reference patents and/or other materials commonly usedfor catheters.

A third electrode ring 20T is mounted on the distal end 12D of outercatheter 12. Wires (not shown) may extend from rings 20F and 20S throughinner catheter 14 and a similar wire (also not shown) may extend withinouter catheter 12 such that all three of the electrode rings 20F, 20S,and 20T may be connected to an electro-cardiographic monitor (not shown)for detection and localization of the conduction tissue. Note that threeelectrode rings are illustrated, but one might alternately use a singlering electrode on the inner catheter 14 and a second ring electrode suchas 20T on the outer catheter 12. Although having a ring electrode suchas 20T on the outer catheter 12 is not necessary for all embodiments ofthe present invention, it is a highly advantageous and important aspectof numerous embodiments of the present invention. In particular, itallows a variation in distance between the ring electrode 20T and one ormore ring electrodes, such as 20F and 20S, which are mounted to theinner catheter 14.

The technique for varying the distance between ring electrode 20T andeither or both of the ring electrodes 20F and 20S will be discussed inmore detail below, but it may be noted that the inner catheter 14 mayslide or translate lengthwise (extending and retracting) as indicatedschematically by the arrows 28T. Additionally, the inner catheter 14 mayrotate relative to outer catheter 12 as indicated by the generallycircular arrows 28R. By having the inner catheter 14 rotatable andtranslatable (extendable) relative to the outer catheter 12, one canposition an anchor point 12A within a patient's heart and then rotateand/or extend inner catheter 14 relative to outer catheter 12 in orderto map a relatively large portion of the patient's heart in order tolocate conduction tissue (heart not shown in FIG. 1). Likewise, once apoint, such as point 12A of outer catheter 12 is anchored within apatient, movement of inner catheter 14 relative to outer catheter 12 maybe used to position inner catheter 14 over a relatively wide area inorder to apply laser energy for ablation of cardiac tissues. Further,although the point 12A would be anchored or relatively stable within thepatient, portions of the outer catheter 12 between point 12A and part14C of inner catheter 14 may be moved in a manner discussed below sothat mapping and/or ablation can be carried out over a relatively widezone without movement of the point 12A.

In order to realize the translational or extension movement of 28T ofthe distal end 14D of inner catheter 14, the proximal end 12P of outercatheter 12 would be secured in position by a clamp (not shown) orsimilar mechanism. This causes the proximal end 14P of inner catheter tobe translated (slide lengthwise) as indicated by arrows 30T. If desired,the proximal end 14P of inner catheter 14 may include variouscircumferential indicia markings 32 along with corresponding numbers orletters (not shown) such that one can easily tell how far the innercatheter 14 has been extended relative to the outer catheter 12. Forexample, the indicia 32 could be read against the proximal edge 34 ofthe outer catheter 12. For ease of illustration, FIG. 1 has shown theproximal edge 34 of outer catheter 12 ending before the outer catheter12 has reached the connector 18. If constructed in that fashion, theconnector 18 would be fixed to the inner catheter 14 at its proximal endportion 14P. However, in practice the outer catheter 12 may have itsproximal end 34 fixed or anchored to the connector 18, in which case theconnector 18 would be fixed relative to the outer catheter 12 and wouldallow the inner catheter 14 to rotate and translate with respect to it.In that case, the connector 18 would supply flushing solution to thecircumferential space between the inner catheter 14 and the inside wallsurface of the outer catheter, the flushing solution exiting at thedistal end of outer catheter 12 where the inner catheter 14 exitstherefrom. (The flushing solution prevents blood from passing from thedistal end to the proximal end in the gap between the outer surface ofinner catheter 14 and the inner surface of outer catheter 12.) If theconnector 18 is fixed to outer catheter 12, the indicia 32 would insteadby disposed at position 32A and could be used for settings by using theback wall 18B of connector 18. In that case, a separate Y-connector (notshown) could be used to supply flushing solution to the inner catheter14.

By rotating the proximal portion 14P of inner catheter 14 as indicatedby generally circular arrows 30R, the distal portion 14D of innercatheter 14 will rotate as shown by arrows 28R relative to the distalportion 12D of outer catheter 12. In order to relatively preciselydetermine the rotational angle of inner catheter 14 relative to outercatheter 12, a marker line 36 may extend lengthwise along a part ofportion 14P and numerals or letters (not shown), such as angularmarkings may be read adjacent to circumferentially spaced lengthwiseextending indicia 38 on the proximal portion 12P of outer catheter 12.The cooperating angular indicia 36 and 38 are shown for the constructionwhere the proximal edge 34 ends before the connector 18. In thealternate arrangement where the connector 18 is fixed relative to theouter catheter 12, lengthwise extending marker 36A may determine angularposition by radially extending indicia 38A on the back wall 18B ofconnector 18.

With reference now to the cross section view of FIG. 2, in which theinner catheter 14 has been deleted for ease of illustration, it will beappreciated that the outer catheter 12 has a generally hollow passageway12H in which the inner catheter 14 (not shown in FIG. 2) would be freeto translate and rotate corresponding to the movements 28T and 28Rrespectively of FIG. 1. In order to facilitate that sliding androtation, hydrophilic lubricants (not shown) would be coated on theouter wall of inner catheter 14 and/or the inner surface of outercatheter 12.

As shown in FIG. 1 and FIG. 2, a coiled spring 40 is disposed along aportion of outer catheter 12. The spring 40 would be at or near thedistal edge (in line with ring electrode 20T in FIG. 1) of the outercatheter 12. The spring 40 is closer to that distal edge than it is tothe proximal edge 34, meaning that all points on the spring 40 arecloser to the edge at ring electrode 20T than the distance from anypoint on the spring 40 to the proximal edge 34.

With reference momentarily to FIG. 3, the outer catheter 12 is shown incross section with spring 40 centered along the lengthwise axis 12X ofouter catheter 12. As shown, the spring 40 may be captured within anincreased diameter portion 42D of the catheter 12, the increaseddiameter portion 42D having a circumferentially extending step edge 42Eat each end of spring 40 (only one end of spring 40 shown in FIG. 3). Byhaving the spring 40 captured within an increased diameter portion 42D,the ability of inner catheter 14 to move within outer catheter 12 willbe maintained without interference from the spring 40. The spring 40 mayoptionally have one or more of its coils, such as back coil 40B, fixedto the inside wall 12N of outer catheter 12.

Referring back to FIG. 2, right and left control wires 44R and 44L,which would be secured to one or more coils of spring 40 adjacent to thedistal end of the spring 40, are used to bend spring 40 and to controlit. By bending the spring 40 and controlling its position, this will inturn control the bend and positioning of outer catheter 12. Controllingouter catheter 12 in this fashion will in turn move the distal end 14Dof inner catheter 14 in a manner described below. The control wires 44Rand 44L are circumferentially spaced around the spiral of the coilspring 40 by 90° to 150°, preferably 105° to 135°. Even more preferably,the range of angular separation between control wire 44R and controlwire 44L would be 115° to 125°, with 120° being the preferred value.

Turning now to FIG. 4, the manner of controlling the control lines 44Rand 44L will be discussed. For ease of illustration, FIG. 4 simply showsa part of the distal portion 14D of the inner catheter 14 with theoutput laser energy 16L indicated, but with the remainder of the innercatheter 14 not illustrated. Likewise, for ease of illustration, theouter catheter is not shown in FIG. 4 so that the spring 40 and controllines 44R and 44L are more easily viewed. A controller 46 serves as acontrol means for bending the coil spring 40 by manipulating the controllines 44R and 44L. The controller 46 includes a sliding assembly 48which may slide relative to a base portion 50. The wires or controllines 44R and 44L are attached to a part of the slide assembly 48. Theslide assembly 48 may be considered as a hand piece which can beextended and retracted as shown for the hand piece extended arrows inFIG. 4. By extending hand piece or slide assembly 48 downward relativeto base 50 in FIG. 4, both control lines 44R and 44L are pulled to causepoint 40F of spring 40 to be folded or bent back towards,the spring inthe manner shown in FIG. 4. Point 40F is seen in FIG. 2 to be midwaybetween control lines 44R and 44L. AS shown in FIG. 4, sufficientpulling on the control lines 44L and 44R will cause the spring 40 tofold into a U shape. Less or reduced movement of hand piece 48 relativeto base 50 may result in a J or similar shape.

Continuing to view FIG. 4, the hand piece or slide assembly 48 includesidentical front and back control knobs 52F and 52B having a shaft 54connected to rotate with the control knobs 52F and 52B. The shaft 54,only a portion of which is shown, has arms 56 fixed on opposite sidesthereof, each control line 44R and 44L connected to a corresponding oneof the arms 56. Upon rotating the control knob such as 52F, the arms 56rotate a corresponding amount so as to increase the pull on one of thecontrol lines and decrease the pull on the other of the control lines.

The effect of rotating the control knob 52F will be better understoodwith reference to FIGS. 5A, 5B, and 5C. With the control knob 52F in theposition of FIG. 5B, both control lines 44R and 44L will be retracted bythe same amount resulting in the orientation illustrated for the distalend 14D of the catheter. In that position, the outer catheter 12 (notshown in FIG. 5B for ease of illustration), as well as the innercatheter 14, would have a bend corresponding to spring 40 of FIG. 5B,which bend lies in a vertical plane (not separately shown) perpendicularto the plane of view of FIG. 5B and centered intermediate the portion ofcontrol lines 44R and 44L as illustrated. Basically, the bend associatedwith coil spring 40 defines a plane in the position of FIG. 5B.

Upon counterclockwise rotation of control knob 52F from its FIG. 5Bposition to assume its FIG. 5A position, the bend associated with coilspring 40 is not planar. Instead, a front portion 58F of coil spring 40is out of the plane corresponding to a back portion 58B of the coilspring 40. In like fashion, the bend in the outer catheter 12 (not shownin FIG. 5A) and the bend in inner catheter 14 would have a configurationcorresponding to that of coil spring 40. In other words, each of thosebends in the inner catheter 14 and outer catheter 12 would benon-planar.

Upon rotating the control knob 52F clockwise from its FIG. 5A positionto its position illustrated for FIG. 5C, the front part 58F of coil 40moves relative to the back part 58B of coil spring 40 in the mannershown. By turning the control knob 52F between its FIG. 5A position andits FIG. 5C position, the distal end 14D of inner catheter 14 moves backand forth in a similar motion to a windshield wiper on a car. Note thata point 40A on coil spring 40 is essentially stationary throughout thepositions of FIGS. 5A, 5B, and 5C as distal portion 14D pivots aboutpoint 40A. The point 40A is also illustrated in FIG. 4 and will beunderstood as being immediately inside the anchor or stationary point12A of FIG. 1. The point 40A would be essentially midway through the180° bend in coil spring 40.

By combining the present invention's ability to place point 12A (referback to FIG. 1) corresponding to point 40A in FIGS. 4, 5A, 5B, and 5C ina relatively stationary position within a patient, with the ability toprovide three different types of movements of distal portion 14D ofinner catheter 14, a relatively large area or zone within a patient'sheart can be mapped for conduction tissue and/or ablated relativelyquickly and efficiently. Specifically, the controller 46 of FIG. 4provides the back and forth or windshield wiper type movementillustrated in FIGS. 5A through 5C, whereas translation 30T and rotation30R (refer back to FIG. 1) provide corresponding extension 28T androtation 28R of the distal portion 14D.

The three types of motion discussed will now be illustrated withreference to FIG. 6 and FIG. 7. However, some background informationwill first be presented relative to cardiac conditions which the presentinvention is especially well suited for. The catheter 10 of FIG. 1 maybe a ventricular arrhythmia ablation catheter designed to be used topercutaneously laser-thermally coagulate arrhythmia foci in the leftventricle of the heart. Designing a catheter for this application issomewhat more difficult than designing a His Bundle (HBA) catheter, asthe HBA catheter does not enter the left ventricle.

A ventricular arrhythmia focus is usually a small portion of viablemyocardium which has been surrounded by scar tissue and is no longer indirect communication with the rest of the heart. A ventriculararrhythmia focus is frequently formed following a heart attack, when aportion of the heart muscle is deprived of its blood supply and dies.This infarcted muscle is replaced by fibrotic scar tissue, not by newmuscle. If a small part of myocardium in the infarcted region manages tosurvive the heart attack, then it has the potential to become anarrhythmia focus. Half of the people who die of heart attacks die as theresult of a ventricular tachyrhythmia or ventricular fibrillation whichoccurs when one of these arrhythmia loci starts to generate its ownpacing signals and causes the heart to start to beat rapidly anduncontrollably. When the heart starts to beat very rapidly (ventricularfibrillation), its pumping efficiency falls dramatically and thearterial blood flow drops to nearly nothing.

It is difficult for cardiologists to localize ventricular arrhythmiafoci in the catheterization laboratory, and currently there is not aneffective catheterization technique to ablate these arrhythmia foci. Theprinciple problem associated with ventricular mapping and arrhythmiafoci ablation is stabilization of the catheter in the left ventricle.The catheters described herein (such as catheter 10) allow a cardiacelectrophysiologist to accurately localize a ventricular arrhythmiafocus and destroy it by applying laser energy to the site andcoagulating the myocardium producing the unwanted and dangerous pacingsignals. Those catheters utilize the electrode guidance and dual-hoodart of the incorporated by reference patents, but also have a steerablesegment, different shapes, and shock-absorbing characteristics of thesteerable segment, shape and catheter material. The three innovationswork in combination to allow precise movement of the catheter tip insidethe ventricle and to prevent the catheter tip from losing contact withthe myocardium during a heart beat.

Although steerability is important, stability is the greater problem. Tobe useful for ventricular mapping and arrhythmia foci ablation, thecatheter must maintain contact with the same portion of the myocardiumduring systole and diastole. These designs address the problem ofstability by their shape and by the compliance of the catheter andspring. The springs such as spring 40 maintain contact between thedistal portion 14D and the wall, even as the heart moves.

The importance of the continuous contact of the catheter with themyocardium cannot be understated. If the catheter were to be pushed awayfrom the heart wall with each contraction and would jolt back into thewall with each heart relaxation, then accurate electrophysiologicmapping of the ventricle would be impossible. Furthermore, each time thecatheter bumps into the heart wall, it is possible to create a prematureventricular contraction which would completely frustrate anyelectrophysiologic exam. With regard to ablation of ventriculararrhythmia foci, if the catheter is not contact with the myocardium,then efficient heating is not possible and arrhythmia ablation cannot beachieved.

Currently, the catheters used for ventricular mapping bend inapproximately a 90° angle and only the very tip of the catheter touchesthe myocardium. These catheters do not always maintain a continuouscontact with the heart wall. They have no shock-absorbing element(unlike the present invention's use of shock absorbing spring 40) andare frequently jolted away from the wall during a ventricularcontraction. Furthermore, these catheters have been used with radiofrequency (RF) energy for ventricular arrhythmia ablation and have notmet with much success. RF energy has a shallow depth of penetration intomyocardium and is unable to coagulate tissues much deeper than 4 or 5mm. The left ventricular wall is up to 1 cm thick, and an arrhythmiafocus may occur at any location in the wall, therefore an RF ablationtechnique would not be able to ablate a focus deep in the LV wall.

With reference now to FIGS. 6 and 7, the point 12A of outer catheter 12may be anchored in or immediately adjacent to the apex 60A of apatient's heart. The translational or extension movement 28T androtational movement 28R of the distal end 14D of inner catheter 14 isillustrated, whereas the windshield wiper like pivoting about point 12Ais illustrated by the difference between position 14D (corresponding toFIG. 5B) and left position 14DL of distal end 14D (corresponding to FIG.5C) and the right position 14DR of 14D (corresponding to position ofFIG. 5A), this sweeping or wiping motion illustrated by arrow 62.

Turning now to FIG. 8, a distal end 114D of a quadripolar ablationcatheter 114 is shown. The catheter 114 may be an inner cathetercooperating with an outer catheter (not shown) in the same manner asdiscussed with respect to the embodiment of FIGS. 1-7. Alternately, theablation catheter 114 may be used without regard to an outer catheter.The components of the catheter 114 are labeled in the 100 series withthe same last two digits as the corresponding component, if any, of theembodiment of FIGS. 1-7. (In similar fashion, all other embodiments willhave the same last two digits as corresponding components from theembodiment of FIGS. 1-7.) For the embodiment of FIG. 8, as well asfurther alternate embodiments discussed below, components will bestructured and operate in the same fashion as the correspondingcomponent in the embodiment of FIGS. 1-7 except where otherwise noted.The window 116, which is an opening, allows passage of laser energy 116Land flushing solution 116F. As illustrated, the window 116 is located inthe middle of four electrode rings 120. That is the window 116 islocated with two electrode rings 120 on one side and two electrode rings120 on the other side. The four electrode rings 120 may provide greaterflexibility in sensing conduction tissue. If the ablation catheter 114of FIG. 8 is used as an inner catheter an additional ring such as ring20T (refer back momentarily to FIG. 1) may also be used to provide evengreater flexibility.

With reference now to FIG. 9, an atrial ventricular (AV) nodal ablationcatheter 214 has a distal portion 214D as illustrated with a window 216delivering laser energy 216L and saline or other flushing solution 216F.In the arrangement of catheter 214, two electrodes 220 are located onthe same side of window 216. In other words, 216 is not located in thezone made up of the electrode rings 220 and the space between theelectrode rings 220. The catheter 214 may, as with all other cathetersdisclosed herein having the last two digits of 14, be used as an innercatheter in the manner illustrated and discussed with respect to FIGS.1-7 and, alternately, be used as a complete catheter (i.e., without useof an outer catheter like outer catheter 12 of FIG. 1). The positioningof window 216 relative to the electrode rings 220 is advantageous fortreatment of AV nodes. (Other of the preferred embodiments for the innercatheter would be suited for treating abnormalities of conduction atdifferent anatomical locations in the heart such as posteriorintraventricular septum, posterior wall, and free left ventricularwall.)

FIG. 10 shows an electrode exit port ablation catheter 314 wherein thedistal end 314D has a window 316 located in the middle one of threeelectrode rings 320. Specifically, the middle ring electrode 320 may becomposed of a cylindrical band of conductive material such as metal andin which a hole corresponding to the size and shape of window 316 hasbeen drilled or otherwise made. The electrode exit port catheter 314 maybe advantageous for treating certain cardiac conditions.

FIG. 11 shows the distal portion 414D of a catheter 414 having electroderings 420 and a window 416 for passage of laser energy 416L and flushingsolution 416F. Catheter 414 is different from catheter 14 in that thewindow 416 has first, second, third, and fourth rubber flapsrespectively labeled 462F, 462S, 462T, and 462R. In FIG. 11, the flapsare in an open position since the flushing solution 416F has pushed themoutward and open due to the pressure with which flushing solution issupplied to the interior of catheter 414. However, FIG. 11A shows eachof the flaps closed such that the window 416 is closed. The flaps, madeof rubber or other resilient material, may each cover one-fourth of thegenerally circular window 416. A greater or larger number of flaps couldalternately be used and the flaps may have some degree of overlap. Whenthe flaps are in the closed position of FIG. 11A, the pressure fromblood or other bodily fluid will be blocked from entering into thecatheter 414 even if no flushing solution is being applied underpressure to the interior of catheter 414. It should also be noted thatthe flaps 462F through 462R could utilize known techniques for makingcheck valves so that each of the flaps may open outwardly, but may notopen inwardly (towards the central lengthwise axis of catheter 414).Although it is contemplated that the pressure of saline or otherflushing solution may be used to open the flaps, the flaps might also bedesigned to open by some other mechanical or electrical control or uponheating from the laser. If laser heating was to be used to open theflaps, each of the flaps might include a bi-metallic plate therein (notshown) which bends upon heating in known fashion.

FIG. 12 shows an ablation catheter 514 with a window 516 and electrodes520. Catheter 514 is different from catheter 14 in that a spring 564,only a portion of which is shown is used to steer the catheter 514. Thespring 564 would be generally similar to the spring 40 of FIG. 1.However, 564 would have some of its coils (not specifically shown)secured to the outside of catheter 514. For example, several of thecoils of spring 564 closest to the proximal end (not shown) of catheter514 may be anchored to the outside of catheter 514. Although not shown,the spring 564 would have control lines similar to control lines 44R and44L connected to one or more of the coils of spring 564 and using acontroller similar to controller 46 of FIG. 4 to provide the illustratedbend. Using the same control technique discussed with respect to FIGS.5A through 5C, the catheter 514 may provide the windshield wiper typemotion depicted in those figures and illustrated as 62 in FIG. 7. Thecatheter 514 may provide that motion without the necessity of using anouter catheter such as 12 of FIG. 1. Spring 564 may be enclosed within acasing (not shown) or mounted within and at the inner diameter of theside wall of catheter 514 (not shown).

With reference now to FIG. 13, an inner catheter 614 is disposed atleast partly within an outer catheter 612. The outer catheter 612 isconstructed identically to outer catheter 12 of FIG. 1. The innercatheter 614 has window 616 and electrode rings 620. The inner catheter614 is constructed like the inner catheter 14 of FIG. 1 except thatinner catheter 614 may rotate (as indicated by arrows 628R) relative toouter catheter 612, but may not translate or extend relative to theouter catheter 612.

FIG. 14 shows the distal end 714D of a catheter 714 having twoelectrodes 720. Additionally, the distal portion 714D includes a firstwindow 716F and a second window 716S, both identically constructed tothe window 16 discussed with respect to FIG. 1. The two windows 716F and716S are offset in a lengthwise direction. Additionally, FIG. 14 showsthe proximal end 714P of catheter 714. As illustrated, the proximalportion 714P has a stop 766 fixed thereon. The optical fiber 722 extendsout a back face 714B of the catheter 714. A member 768 is secured to theoptical fiber 722. When the member 768 abuts the back surface 714B, thetip of the optical fiber 722 will be adjacent the first window 716 inorder to supply laser energy out that window. The optical fiber 722 isslidably received within the catheter 714 such that pulling the member768 pulls the optical fiber 722. When the member 768 abuts the stopsurface 766S of member 766, the tip of the optical fiber 722 will beadjacent the window 716S such that laser energy may be passed throughthat window. This provides flexibility in the relationship between theport or opening used to supply the laser energy and the electrode rings720.

With reference now to the side view of distal portion 714D in FIG. 15, afurther feature of the ring electrodes 720 is illustrated. (Althoughonly one ring electrode 720 is in FIG. 15, it will be understood thatboth ring electrodes 720 would be configured in the same fashion. Asillustrated in FIG. 15, a part of the ring electrode 720 at the backpart 714K of catheter 714 is covered by epoxy or other insulatingmaterial 770. Accordingly, only the contact surfaces of ring electrodes720 which are not covered by the insulating material 770 will beconducting current upon contacting the patient's heart (not shown inFIG. 15). This arrangement, which may be incorporated into all of theother embodiments having ring electrodes, allows one to better insurethat the window, such as window 716F of FIG. 15, is pointing towards thecardiac tissues. As illustrated in FIG. 15, the back half or 180° of thering electrode 720 may be covered with insulating material 770. However,the portion of the ring electrode 720 which is covered with insulatingmaterial may be greater or less than 180°. The portion covered byinsulating material 770 would preferably be centered radially oppositethe center of the window such as window 716F. The angular extent of ringelectrode 720 which is covered by insulating material 720 determines howprecisely one may insure that the window 716F is facing the conductiontissue sensed by ring electrodes such as ring electrodes 720.

With reference now to FIG. 16, a laser ablation catheter 814 is shownapplying laser energy 816L from window 816 to the left ventricular wall860LV of a patient's heart 860. The ablation catheter 814 is bent intothe shape as shown by a spring 840 which may be disposed within an outercatheter (not shown in FIG. 16 for ease of illustration). The spring 840may be attached to such an outer catheter in the manner discussed withrespect to the FIG. 1 embodiment. Alternately, the spring 840 could beencased within the side wall of catheter 814. In either case, thecatheter 814 has non-homogeneous flexibility with a flexible portion772F along with a less flexible section 772R. The catheter 814 isrelatively straight when initially disposed near the wall 860LV. Controllines (not shown) are used to initially bend the spring 840 in the Lbend shown in FIG. 16. As the bend is placed in the catheter 814, thewindow 816 and electrode rings 820 maintain relatively close contactwith the wall 860LV since the bend occurs in relatively flexible portion772F and the less flexible or rigid portion 772R (which extends fromportion 772F to the furthest ring electrode 820) stays in a relativelystraight line. As discussed previously with respect to spring 40 of FIG.1, the spring 840 serves as a shock absorber to maintain contact betweenring electrodes 820 and the wall 860LV even when the heart is beating.

The operation of the catheter 814 of FIG. 16 will be discussed withreference to FIGS. 17A, 17B, and 17C showing different positions of acontrol knob 852F (which would be part of an assembly such as assembly46 of FIG. 4) and the corresponding positions of distal portion 814D andspring 840 as control knob 852F manipulates control lines 844R and 844L.In all of the positions illustrated in FIGS. 17A through 17C, the laserenergy 816L will be applied perpendicular and into the plane of view.The operation of control knob 852F to provide a windshield wiper typemovement (pivoting of distal portion 814D about anchor point 840A)illustrated between FIGS. 17A and 17C is essentially the same asdiscussed above with respect to FIGS. 5A through 5C except that theshape of the bend in spring 840 is different and the correspondingorientation of the distal end 814D is somewhat different.

It should be readily appreciated that other steering mechanisms thanthat shown could be used for the outer catheter 12 of FIG. 1. Althoughnot illustrated, an alternate arrangement of outer catheter 12 wouldinclude two passageways instead of the one passageway 12H of FIG. 2. Oneof the passageways would hold the inner catheter, whereas the otherpassageway could hold a separate steering mechanism different from thatshown and discussed.

Although various specific constructions have been illustrated herein, itis to be understood that these are for illustrative purposes only.Various adaptations and modifications will be apparent to those of skillin the art. According, the scope of the present invention should bedetermined by reference to the claims appended hereto.

What is claimed is:
 1. A catheter comprising:a housing with a side wall;a first window in said side wall; an optical fiber having a tip, saidfirst window positioned such that light may pass between said tip andsaid first window; and lengthwise offset first and second electrodesmounted to said side wall and operable for detecting the presence ofconductive cardiac tissue; andwherein said side wall includes first andsecond portions on which said first and second electrodes arerespectively disposed, and said first portion is movable relative tosaid second portion to vary a distance between said first and secondelectrodes and further comprising an outer catheter portion having aproximal end and a distal end having at least a first passage extendinglengthwise therein, said outer catheter portion having said firstportion with said first electrode mounted thereon; an inner catheterportion disposed at least partly in said first passage and having aproximal end and a distal end, said inner catheter portion having saidside wall with said first window therein, said inner catheter portionhaving an extending portion extendable out said distal end of said outercatheter portion by a variable amount, said inner catheter portionhaving said second portion with said second electrode mounted thereon.2. The apparatus of claim 1 wherein said first window is lengthwiseoutside a zone including said first and second electrodes and a spacetherebetween.
 3. The apparatus of claim 1 further comprising a coilspring mounted near said distal end of said outer catheter portion, saidcoil spring operable to secure an anchor point on said outer catheterportion stationary within a patient while said extending portion of saidinner catheter is extended.
 4. The catheter of claim 1 furthercomprising a second window in said side wall lengthwise offset from saidfirst window and a member secured to a proximal end of said opticalfiber to allow movement of said optical fiber relative to said housingbetween a position to pass light between said tip and said first windowand a position to pass light between said tip and said second window. 5.The catheter of claim 1 wherein said first window is an opening havingat least a first valve member for selectively opening and closing saidfirst window.
 6. The catheter of claim 1 wherein said first and secondelectrodes have contact surfaces which are limited to an angular rangeexcluding at least a back part of said side wall radially opposite saidfirst window.
 7. A catheter comprising:a housing with a side wall; afirst window in said side wall; an optical fiber having a tip, saidfirst window positioned such that light may pass between said tip and ofsaid first window; and lengthwise offset first and second electrodesmounted to said side wall and operable for detecting the presence ofconductive cardiac tissue; andwherein said first and second electrodeshave contact surfaces which are limited to an angular range excluding atleast a back part of said side wall radially opposite said first window.8. The apparatus of claim 7 wherein said first window is lengthwiseoutside a zone including said first and second electrodes and a spacetherebetween.
 9. A catheter comprising:a housing with a side wall; afirst window in said side wall; an optical fiber having a tip, saidfirst window positioned such that light may pass between said tip andsaid first window; and lengthwise offset first and second electrodesmounted to said side wall and operable for detecting the presence ofconductive cardiac tissue; andwherein said first window is lengthwiseoutside a zone including said first and second electrodes and a spacetherebetween.
 10. The catheter of claim 9 further comprising lengthwiseoffset third and fourth electrodes mounted to said side wall andoperable for detecting the presence of conductive cardiac tissue, saidthird and fourth electrodes located on a side of said first windowopposite to said first and second electrodes.
 11. The apparatus of claim10 wherein said first window is lengthwise outside a zone including saidfirst and second electrodes and a space therebetween.
 12. A cathetercomprising:a housing with a side wall; a first window in said side wall;an optical fiber having a tip, said first window positioned such thatlight may pass between said tip and said first window; and lengthwiseoffset first and second electrodes mounted to said side wall andoperable for detecting the presence of conductive cardiac tissue;andwherein said first electrode has a contact surface completelysurrounding said first window.
 13. The apparatus of claim 12 whereinsaid housing includes:an outer catheter portion having a proximal endand a distal end having at least a first passage extending lengthwisetherein; an inner catheter portion disposed at least partly in saidfirst passage and having a proximal end and a distal end, said innercatheter portion having said side wall with said first window therein,said inner catheter portion having an extending portion extendable outsaid distal end of said outer catheter portion by a variable amount;andfurther comprising a coil spring mounted near said distal end of saidouter catheter portion, said coil spring operable to secure an anchorpoint on said outer catheter portion stationary within a patient whilesaid extending portion of said inner catheter is extended.
 14. Theapparatus of claim 12 wherein said first electrode has a hole thereinand said first window is within said hole of said first electrode.
 15. Acatheter comprising:a housing with a side wall; a first window in saidside wall; an optical fiber having a tip, said first window positionedsuch that light may pass between said tip and said first window; andlengthwise offset first and second electrodes mounted to said side walland operable for detecting the presence of conductive cardiac tissue;andwherein said first window is an opening having at least a first valvemember for selectively opening and closing said first window.
 16. Theapparatus of claim 15 wherein said first valve member opens underpressure to allow fluid to flow out said first window and closes underpressure to block fluid from flowing into said first window.
 17. Theapparatus of claim 15 wherein said first valve member is operable as acheck valve.
 18. The apparatus of claim 15 wherein said first valvemember is one of a plurality of valve members which selectively open andclose said first window.
 19. A catheter comprising:a housing with a sidewall; a first window in said side wall; an optical fiber having a tip,said first window positioned such that light may pass between said tipand said first window; and lengthwise offset first and second electrodesmounted to said side wall and operable for detecting the presence ofconductive cardiac tissue; andfurther comprising a second window in saidside wall lengthwise offset from said first window, and wherein saidoptical fiber is movable relative to said housing between a position topass light between said tip and said first window and a position to passlight between said tip and said second window.
 20. The apparatus ofclaim 19 wherein said first window is lengthwise outside a zoneincluding said first and second electrodes and a space therebetween.